"""Support for exposing a templated binary sensor."""
import logging
from itertools import chain

import voluptuous as vol

from homeassistant.core import callback
from homeassistant.components.binary_sensor import (
    BinarySensorDevice,
    ENTITY_ID_FORMAT,
    PLATFORM_SCHEMA,
    DEVICE_CLASSES_SCHEMA,
)
from homeassistant.const import (
    ATTR_FRIENDLY_NAME,
    ATTR_ENTITY_ID,
    CONF_VALUE_TEMPLATE,
    CONF_ICON_TEMPLATE,
    CONF_ENTITY_PICTURE_TEMPLATE,
    CONF_SENSORS,
    CONF_DEVICE_CLASS,
    EVENT_HOMEASSISTANT_START,
    MATCH_ALL,
)
from homeassistant.exceptions import TemplateError
import homeassistant.helpers.config_validation as cv
from homeassistant.helpers.entity import async_generate_entity_id
from homeassistant.helpers.event import async_track_state_change, async_track_same_state

_LOGGER = logging.getLogger(__name__)

CONF_DELAY_ON = "delay_on"
CONF_DELAY_OFF = "delay_off"
CONF_ATTRIBUTE_TEMPLATES = "attribute_templates"

SENSOR_SCHEMA = vol.Schema(
    {
        vol.Required(CONF_VALUE_TEMPLATE): cv.template,
        vol.Optional(CONF_ICON_TEMPLATE): cv.template,
        vol.Optional(CONF_ENTITY_PICTURE_TEMPLATE): cv.template,
        vol.Optional(CONF_ATTRIBUTE_TEMPLATES): vol.Schema({cv.string: cv.template}),
        vol.Optional(ATTR_FRIENDLY_NAME): cv.string,
        vol.Optional(ATTR_ENTITY_ID): cv.entity_ids,
        vol.Optional(CONF_DEVICE_CLASS): DEVICE_CLASSES_SCHEMA,
        vol.Optional(CONF_DELAY_ON): vol.All(cv.time_period, cv.positive_timedelta),
        vol.Optional(CONF_DELAY_OFF): vol.All(cv.time_period, cv.positive_timedelta),
    }
)

PLATFORM_SCHEMA = PLATFORM_SCHEMA.extend(
    {vol.Required(CONF_SENSORS): cv.schema_with_slug_keys(SENSOR_SCHEMA)}
)


async def async_setup_platform(hass, config, async_add_entities, discovery_info=None):
    """Set up template binary sensors."""
    sensors = []

    for device, device_config in config[CONF_SENSORS].items():
        value_template = device_config[CONF_VALUE_TEMPLATE]
        icon_template = device_config.get(CONF_ICON_TEMPLATE)
        entity_picture_template = device_config.get(CONF_ENTITY_PICTURE_TEMPLATE)
        entity_ids = set()
        manual_entity_ids = device_config.get(ATTR_ENTITY_ID)
        attribute_templates = device_config.get(CONF_ATTRIBUTE_TEMPLATES, {})

        invalid_templates = []

        templates = {
            CONF_VALUE_TEMPLATE: value_template,
            CONF_ICON_TEMPLATE: icon_template,
            CONF_ENTITY_PICTURE_TEMPLATE: entity_picture_template,
        }

        for tpl_name, template in chain(templates.items(), attribute_templates.items()):
            if template is None:
                continue
            template.hass = hass

            if manual_entity_ids is not None:
                continue

            template_entity_ids = template.extract_entities()
            if template_entity_ids == MATCH_ALL:
                entity_ids = MATCH_ALL
                # Cut off _template from name
                invalid_templates.append(tpl_name.replace("_template", ""))
            elif entity_ids != MATCH_ALL:
                entity_ids |= set(template_entity_ids)

        if manual_entity_ids is not None:
            entity_ids = manual_entity_ids
        elif entity_ids != MATCH_ALL:
            entity_ids = list(entity_ids)

        if invalid_templates:
            _LOGGER.warning(
                "Template binary sensor %s has no entity ids configured to"
                " track nor were we able to extract the entities to track"
                " from the %s template(s). This entity will only be able"
                " to be updated manually.",
                device,
                ", ".join(invalid_templates),
            )

        friendly_name = device_config.get(ATTR_FRIENDLY_NAME, device)
        device_class = device_config.get(CONF_DEVICE_CLASS)
        delay_on = device_config.get(CONF_DELAY_ON)
        delay_off = device_config.get(CONF_DELAY_OFF)

        sensors.append(
            BinarySensorTemplate(
                hass,
                device,
                friendly_name,
                device_class,
                value_template,
                icon_template,
                entity_picture_template,
                entity_ids,
                delay_on,
                delay_off,
                attribute_templates,
            )
        )
    if not sensors:
        _LOGGER.error("No sensors added")
        return False

    async_add_entities(sensors)
    return True


class BinarySensorTemplate(BinarySensorDevice):
    """A virtual binary sensor that triggers from another sensor."""

    def __init__(
        self,
        hass,
        device,
        friendly_name,
        device_class,
        value_template,
        icon_template,
        entity_picture_template,
        entity_ids,
        delay_on,
        delay_off,
        attribute_templates,
    ):
        """Initialize the Template binary sensor."""
        self.hass = hass
        self.entity_id = async_generate_entity_id(ENTITY_ID_FORMAT, device, hass=hass)
        self._name = friendly_name
        self._device_class = device_class
        self._template = value_template
        self._state = None
        self._icon_template = icon_template
        self._entity_picture_template = entity_picture_template
        self._icon = None
        self._entity_picture = None
        self._entities = entity_ids
        self._delay_on = delay_on
        self._delay_off = delay_off
        self._attribute_templates = attribute_templates
        self._attributes = {}

    async def async_added_to_hass(self):
        """Register callbacks."""

        @callback
        def template_bsensor_state_listener(entity, old_state, new_state):
            """Handle the target device state changes."""
            self.async_check_state()

        @callback
        def template_bsensor_startup(event):
            """Update template on startup."""
            if self._entities != MATCH_ALL:
                # Track state change only for valid templates
                async_track_state_change(
                    self.hass, self._entities, template_bsensor_state_listener
                )

            self.async_check_state()

        self.hass.bus.async_listen_once(
            EVENT_HOMEASSISTANT_START, template_bsensor_startup
        )

    @property
    def name(self):
        """Return the name of the sensor."""
        return self._name

    @property
    def icon(self):
        """Return the icon to use in the frontend, if any."""
        return self._icon

    @property
    def entity_picture(self):
        """Return the entity_picture to use in the frontend, if any."""
        return self._entity_picture

    @property
    def is_on(self):
        """Return true if sensor is on."""
        return self._state

    @property
    def device_class(self):
        """Return the sensor class of the sensor."""
        return self._device_class

    @property
    def device_state_attributes(self):
        """Return the state attributes."""
        return self._attributes

    @property
    def should_poll(self):
        """No polling needed."""
        return False

    @callback
    def _async_render(self):
        """Get the state of template."""
        state = None
        try:
            state = self._template.async_render().lower() == "true"
        except TemplateError as ex:
            if ex.args and ex.args[0].startswith(
                "UndefinedError: 'None' has no attribute"
            ):
                # Common during HA startup - so just a warning
                _LOGGER.warning(
                    "Could not render template %s, " "the state is unknown", self._name
                )
                return
            _LOGGER.error("Could not render template %s: %s", self._name, ex)

        templates = {
            "_icon": self._icon_template,
            "_entity_picture": self._entity_picture_template,
        }

        attrs = {}
        if self._attribute_templates is not None:
            for key, value in self._attribute_templates.items():
                try:
                    attrs[key] = value.async_render()
                except TemplateError as err:
                    _LOGGER.error("Error rendering attribute %s: %s", key, err)
            self._attributes = attrs

        for property_name, template in templates.items():
            if template is None:
                continue

            try:
                setattr(self, property_name, template.async_render())
            except TemplateError as ex:
                friendly_property_name = property_name[1:].replace("_", " ")
                if ex.args and ex.args[0].startswith(
                    "UndefinedError: 'None' has no attribute"
                ):
                    # Common during HA startup - so just a warning
                    _LOGGER.warning(
                        "Could not render %s template %s," " the state is unknown.",
                        friendly_property_name,
                        self._name,
                    )
                else:
                    _LOGGER.error(
                        "Could not render %s template %s: %s",
                        friendly_property_name,
                        self._name,
                        ex,
                    )
                return state

        return state

    @callback
    def async_check_state(self):
        """Update the state from the template."""
        state = self._async_render()

        # return if the state don't change or is invalid
        if state is None or state == self.state:
            return

        @callback
        def set_state():
            """Set state of template binary sensor."""
            self._state = state
            self.async_schedule_update_ha_state()

        # state without delay
        if (state and not self._delay_on) or (not state and not self._delay_off):
            set_state()
            return

        period = self._delay_on if state else self._delay_off
        async_track_same_state(
            self.hass,
            period,
            set_state,
            entity_ids=self._entities,
            async_check_same_func=lambda *args: self._async_render() == state,
        )

    async def async_update(self):
        """Force update of the state from the template."""
        self.async_check_state()
